Sunday, March 24, 2013

In the schedule of a working dad, the opportunities for mucking around with your own bike are always few and far between. The new bottom bracket and chainset have been with me for weeks now, but circumstances and the freezing cold weather have meant that I have not fitted them.

The Octalink bottom bracket was chosen, partly because I wanted to fit a Tiagra chainset at the front. Tiagra as a component quality is the road bike equivalent of a rough and tumble mountain bike. The component group often being used on touring bikes and long range commuters.

Octalinks are Shimano's evolution of the square tapered bracket. Instead of a square taper for the crank arm, the crank arm is splined partly to give better purchase and transmission of the crank arm on to the bottom bracket. Partly to have a patented pattern that other manufacturers couldn't copy and so lock users into one make of component. It's an evolution that works as looking through the parts list it was getting harder and harder to find one that wasn't Octalink or ISIS based. Which in itself is silly becuase the square taper is effectively bomb proof and easier to manufacture. But I guess in a modern world looking for lightness and the next best thing everyone is happy to be tied into one manufacturer.

So the bottom bracket was an easy fit after some further cleaning and degreasing to make sure the threads were free of dirt. The it was just a case of grease, grease and more grease to the threads and slot on the splines. One thing though: more work. I have gone for a bigger number of teeth so I need to replace the chain (which is now too short), and the front mech will need re-aligning, and a new cable to cope with any additional pull as I have not left much play in the current one. I may also need to sort out the chainline which may differ, but I will check that later.

The chain has been replaced with a SRAM 9 speed, because after mucking around with all those pins on the Shimano I can't be bothered spending another £5 because the pins won't insert straight and break. The powerlink clip makes it much easier to work with and has the advantage of if I change any of the gear ratios I will be able to shorten quickly and easily without fuss.

Saturday, March 2, 2013

Generally, I find that once I have completed a series off tasks designed to correct a fault everything starts to go swimmingly. The issue with the chainset on the Ridgeback Adventure 520SX had left me a little stumped. What do I replace it with? Do I stick with the three at the front or move to a two ring configuration. Do I keep the old bottom bracket which although not showing signs of wear is many miles old and will need replacing sooner or later? If I replace do I stick with the sealed cartridge bottom bracket or adopt the Octalink version for which more chainsets are available for 9 speed set ups?

I spent a lot of time kicking these ideas about and thinking I will need to get the bottom bracket off just to check the BB size when.....I found myself on a gentle training ride with my foot attached to the pedal but the pedal no longer attached to the crank arm. The cheap light aluminum arm that had come with the bike back in those oh so dark 1990's had finally worn away against the better tensile strength of my pedals. OK fine so now I have to replace the lot. Might as well clean it all up and start again.

But although I got the non-drive crankarm off easily using the crank puller the same couln't be said for the drive side. Years of use and grime has finally caught up and bit me on the butt. I should have paid attention and taken these off and cleaned them. It takes a lot of leverage and a large amount of penetrating oil (not a light oil like WD40 but a lube containing graphite) and some patience to finall be able to extract the drive side. This can go in the scrap metal recycling there is nothing that can be re-used here.

Now for the bottom bracket and no surprise here again it proves troublesome to remove the drive side, and this is all the time remembering that drive side threads on a bicycle are all left handed. In otherwords the reverse of conventional "righty tighty lefty loosey". Lots of cleaning fluid and degreaser needed to be used along with doses on penetratiing oil until finally the grit and grime are removed and the seals are broken. For good measure I applied a few light taps to break any metal on metal bonding. No idea if this works, but it did seem like a good idea just in case.

So now all is stripped out and the bottom bracket is undergoing a full degrease and clean ready to accept a new bottom bracket. I know the size, 68mm as suspected, but the decision now needs to be made as to which one?

So the last post was almost prophetic in its tone. More haste less speed. I finally had to drop into the granny ring (smallest front chainring) on the Adventure the other day. The result on a steep incline was to suddenly stop as the chain stuck and held fast on a cog. Ouch. It is funny but running the bike off the floor on a workstand there was a little stickiness which I took to just be stiff linkers that would work out overtime. Under real pedal tension it appears that this is more serious. Four cogs grip the chain by being too wide for the 9-speed chain. Perhaps a little more careful investigation at the start would have presented the embarrassment of falling off on the hill.

P3 rebuild

current state of play

about the blog

Professor Dawkins has suggested that the act of creation is like a blind watchmaker. I have explored this idea in building a bike from second hand parts. Like the blind watchmaker I have had no idea of what is the next stage or even the correct component. Unlike the blind watchmaker I have the internet and suddenly it was a whole lot quicker.